1. Field of the Invention
The present invention relates to the field of integrated circuits. More particularly, the invention provides a method of integrating a heat sink within the structure of a multi-layer printed circuit board.
2. Description of the Related Art
A multi-layer printed circuit board (PCB) is a composite of organic and inorganic materials with external and internal conductors, allowing electronic components to be mechanically supported and electrically connected. A PCB typically contains multiple planar insulation layers interweaved with multiple planar metal layers. As illustrated in FIG. 1, an exemplary PCB 11 contains at least one metal layer 13 (device plane) that is patterned to transfer signals between the electronic components, one power plane 15 for distributing voltage throughout the PCB, and one ground plane 17, with planar insulating layers 19, 21, 23 located between the metal layer, power plane and ground plane, and on a bottom surface of PCB 11.
As integrated circuit technology has improved, substantially greater functionality has been incorporated into the electronic components such as integrated circuit processors, memories, logic devices, etc. which are mounted on PCB 11. In addition, the portability of computing and information management is driving the reduction in size from desktop to laptop to notebook sized products. Hence, as integrated circuits have expanded in functionality and become more complex with denser circuit packing, their size has also diminished resulting in increased power consumption and greater heat dissipation in physically smaller areas. Thus, modern integrated circuits generate more heat while possessing smaller surface areas to dissipate the heat.
To improve thermal efficiency, many package designs today employ additional structures to dissipate heat during the operation of the integrated circuit device. Many such structures are formed by attaching additional heat dissipating surfaces to the ground or power planes of a printed circuit board or directly to an integrated circuit device itself Heat pipes and other heat removal devices are also often employed. The manufacturing and assembly costs associated with the use of additional structures for heat removal can be quite high.
What is needed is a relatively low cost technique which solves the aforementioned problems associated with removing heat from an integrated circuit device.